Age resistor for rubber



Patented Jan. 13', 1931 i 9 wILLm'rrn. woman, or CUYAHOGA mm, oHro-,.AssIeNoR-;rornneoon nnnj'rrma I I v PATENT Q H a RUBBER comrnnmon AK'RON', our-eye: connonArrIoN-on-omo a r we RESISTOR non RUBBER.

. 1B1- Drawing.

.This: inventionrelates to the preparation of novel rubber compounds. and it has particular relation to the preparationof compounds thartfare materially morecdurable than those 5 ordinarily employed in the industry.

Qne object of the. invention is.-,to'.-provide a method. of treating, rubber compounds which results in a material increaseof: the resistance of the compound totheaction' of oxygen; and other agencies which heretofore have caused premature: deterioration of the rubber. 7 .7

,Another objectof the invention is to provide a method of treating rubber compounds 7 which involves the useofcertain by-p'roducts "2 ganic materials known to the industry as antioxidants, or age-retarders. Among the materials which have been suggested are the following: hydroquinone, diphenyl amine,

and reaction products of certain aldehydes I 0 with amino bodies, a specific example of the V latter type of compounds being the reaction product of aldol and naphthylamine. Most of the compounds heretofore tried, while exhibiting some tendency to retard the action of oxygen upon the rubber, have been undesirable 1n certain respects. 7

For example, some of them were observed a to be unduly toxic to the workmen employed in handling them. Still others possessed 40 strongand disagreeable odors which necessitated the installation of special ventilating equipment in the factories where they were used. Others were of tarry nature and were difiicult to incorporate into the rubber. Also,- 48 most of the materials heretofore employed Application filed'November 6,1929. Serial 1%. 405,280.

were manufactured from basic ingredients for wh ch there was; considerable demand forother purposes in the industry. Therefore,

the ingredients were relatively expensive to obtain. 3 r V TlllS lnventio'n consists in the discovery that a highly satisfactory antioxidant-may be obtained from parahyd-roxy diphenyl by subjecting that. compound to nitration and reduction by means of, ordinary and wellknown methods. Nitration is preferably effected by subjecting hydroxy diphenyl dissolved in alcohol. to vthe actionof. nitric acid,

a temperature of 50? to 60. G. being/employed during the: course of the reaction. The solution containing the reactionproduct, consisting essentially of mono nitro hydroxy diphenyl, is neutralized with a solution of 5% sodium hydroxide, after which it may be reduced to the corresponding amino compound by means of sodium hydrosulfite. In this reaction, approximately molecular proportions of they basic ingredients entering into the combination, are employed. The

.m-echanics off-the.reaction maybe, represented by the following equation I The position ofthe nitroand amino groups in thejcompounds has not been definitely established. However, it"seems to be in the same nucleus as thehydroxy gro The material obtained by the above. de} scribed reactions is in a relatively high state of}. purity,,.and for commercial, purposes it onlynece's'sary to subject itto washingjwith watertoaobtain it such; form that, it may hydroxy diphenylp repared in accordance ,besub-jectedfto. immediate use. The amino with the precedingmethod may be employed successfully as an antioxidant in most of the standard rubber compounds. However, the

followingis an example of a formula inf which it has been found to be particularly successful: 7 r 1 P- t Acetone extracted rubber 100 Zinc oxide l 5 Sulphur 3 Stearic acid 1.5 Hexa methylene tetramine 1 Amino p-hydroxy diphenyL 1 Samples of rubber prepared in accordance with the preceding formula were subjected tov vulcanization for varying periods of time. These samples were then divided into two identical sets, one of which was immediately subjected to physical testsin order to ascertainthe tensile strength and elasticity thereof prior to ageing. The second set was first weighed, and then vplaced. in an oxygen bomb and subjected to'the action of oxygen gas under a pressure of 15.0 pounds per square inch, and at a temperature of 50 C. for a period of six days. The results of these tests are tabulated as'follows:

Ammo hydrozry diphenyl ORIGINAL Cure 7 Load KgCM at Elong. Gain break in wt. Time if T9111 500% 700% Tenin in mins. F. elong. elong. sile .AFTER AGEING hydroxy diphenyl.

2. A method of preserving rubber which comprises. incorporating therein a reduction product ofj'nitro hydroxy diphenyl.

"3. A method of preserving rubber which comprises subjecting it to'vulcanizationin the presence of a material prepared by the nitration and reduction of hydroxy diphenyl.

' 4. A method of preserving rubber which comprises subjecting it to vulcanization in the presence of mono amino hydroxy diphenyl. I 53A rubber product that has been Vulcan ized in the presence of mono amino hydroxy diphenyl} I I 6. A'rubber product that has been vulcanizedfin the presence of amino hydroxy diphenyl, F i r Y 7. -A rubber product that has been vulcaniz'ed in the presence of a reduction product of mono nitro hydroxy diphenyl. y

8. A rubber product that has been vulcanized' in the presence of a material prepared by the nitration and subsequent reduction of hydroxy diphenyl. V

In witness whereof, I have hereunto signed my name. 7

Signed atAkron, in the county of Summit and State of Ohio, U. S. A., this 4th day of November, 1929.

Y Y WILLIAM D. WOLFE.

From-the above data itjwill be apparentthat rubber compounds containing amino hyto a remarkable degree, and samples of the material retain the major portion of their elasticity even under the severeconditions existing during the bomb tests. 'Also, the per centages of oxygen absorbed during the course of the test are comparatively slight. Under similar conditions, samples of rubber containing no antioxidant arereduced to resinous masses substantially devoid of elasticity and. tensile strength and containing very high percentages of oxygen. The antioxidant'is highly desirable fr oma commercial standpoint because the toxicity is low or nil and the compound'is practically non.-

I droxy diphenyl resist the action of oxygen odorous; The compound is relatively stable U and may be obtained in highly pure state.

For that reason uniform results are obtained by its use; 

